Date Updated: 05/07/2022

Alzheimer's dementia can be diagnosed in several different ways. Often, Alzheimer's is diagnosed through a doctor's exam. They will evaluate your signs and symptoms and do several tests. They may talk to friends and family members to find out more about symptoms and behavior.

It's important to get an accurate diagnosis of Alzheimer's, the most common type of dementia. The correct diagnosis is an important first step toward getting the appropriate treatment, care, family education and plans for the future.

Early signs and symptoms of Alzheimer's dementia

Early signs and symptoms of Alzheimer's dementia include:

  • Memory impairment, such as difficulty remembering events
  • Difficulty concentrating, planning or problem-solving
  • Problems finishing daily tasks at home or at work, such as writing or using eating utensils
  • Confusion with location or passage of time
  • Having visual or space difficulties, such as not understanding distance in driving, getting lost or misplacing items
  • Language problems, such as word-finding problems or reduced vocabulary in speech or writing
  • Using poor judgment in decisions
  • Withdrawal from work events or social engagements
  • Changes in mood, such as depression or other behavior and personality changes

Alzheimer's dementia can affect several aspects of your daily life.

When warning signs of Alzheimer's dementia appear, it's important that you get a prompt and accurate diagnosis.

Diagnosing Alzheimer's dementia

To diagnose Alzheimer's dementia, your primary doctor, a doctor trained in brain conditions (neurologist) or a doctor trained to treat older adults (geriatrician) will review your symptoms, medical history, medication history and interview someone who knows you well such as a close friend or family member. Your doctor will also perform a physical examination and conduct several tests.

During your appointment, your doctor will evaluate:

  • Whether you have impaired memory or thinking (cognitive) skills
  • Whether you exhibit changes in personality or behaviors
  • The degree of your memory or thinking impairment or changes
  • How your thinking problems affect your ability to function in daily life
  • The cause of your symptoms

Doctors may order additional laboratory tests, brain-imaging tests or send you for detailed memory testing. These tests can provide doctors with useful information for diagnosis, including ruling out other conditions that cause similar symptoms.

Ruling out other conditions

Doctors will perform a physical evaluation and check that you don't have other health conditions that could be causing or contributing to your symptoms, such as signs of past strokes, Parkinson's disease, depression, sleep apnea or other medical conditions.

Assessing memory problems and other symptoms

To assess your symptoms, your doctor may ask you to answer questions or perform tasks associated with your cognitive skills, such as your memory, abstract thinking, problem-solving, language usage and related skills.

  • Mental status testing. Your doctor may conduct mental status tests to test your thinking (cognitive) and memory skills. Doctors use the scores on these tests to evaluate your degree of cognitive impairment.
  • Neuropsychological tests. You may be evaluated by a specialist trained in brain conditions and mental health conditions (neuropsychologist). The evaluation can include extensive tests to evaluate your memory and thinking (cognitive) skills.

    These tests help doctors determine if you have dementia, and if you're able to safely conduct daily tasks such as taking medications as scheduled and managing your finances. They provide information on what you can still do as well as what you may have lost. These tests can also evaluate if depression may be causing your symptoms.

  • Interviews with friends and family. Doctors may ask your family member or friend questions about you and your behavior.

    Doctors look for details that don't fit with your former level of function. Your family member or friend often can explain how your thinking (cognitive) skills, functional abilities and behaviors have changed over time.

This series of clinical assessments, the physical exam and the setting (age and duration of progressive symptoms) often provide doctors with enough information to make a diagnosis of Alzheimer's dementia. However, when the diagnosis isn't clear, doctors may need to order additional tests.

Laboratory tests

You may have laboratory tests to rule out other disorders that cause some symptoms similar to those of Alzheimer's dementia, such as a thyroid disorder or vitamin B-12 deficiency.

Your doctor may recommend a cerebrospinal fluid examination to help with the diagnosis. Amyloid and tau proteins can be measured in the cerebrospinal fluid. The ratio of these proteins can help determine whether Alzheimer's is present. In most cases of Alzheimer's disease, a cerebrospinal fluid examination is not necessary, but in atypical or rapidly progressive cases it may be useful.

Brain imaging tests

Alzheimer's dementia results from the progressive loss (degeneration) of brain cells. This degeneration may show up in a variety of ways in brain scans.

However, these scans alone aren't enough to make a diagnosis. Scans aren't used to diagnose the condition because there is overlap in what doctors consider normal age-related change in the brain and abnormal change.

However, brain imaging can help:

  • Rule out other causes, such as hemorrhages, brain tumors or strokes
  • Distinguish between different types of degenerative brain disease
  • Establish a baseline about the degree of degeneration

The brain-imaging technologies most often used are:

  • Magnetic resonance imaging (MRI). An MRI uses powerful radio waves and magnets to create a detailed view of your brain.
  • Computerized tomography (CT). A CT scan uses X-rays to obtain cross-sectional images of your brain.
  • Positron emission tomography (PET). A PET scan uses a radioactive substance known as a tracer to detect substances in the body. There are different types of PET scans. The most commonly used PET scan is a fluorodeoxyglucose (FDG) PET scan. This scan can identify brain regions with decreased glucose metabolism. The pattern of metabolism change can distinguish between different types of degenerative brain disease.

    PET scans have recently been developed that detect clusters of amyloid proteins (plaques) or tau (neurofibrillary tangles), which are associated with Alzheimer's dementia. These types of PET scans are typically used in the research setting.

Future of diagnosis

Researchers are working on new ways to diagnose Alzheimer's dementia earlier. New tests might be able to diagnose the disease when symptoms are very mild or even before symptoms start. Currently, researchers are developing tests that measure amyloid or tau in the blood. These tests are promising and may be used to determine who is at risk of Alzheimer's dementia, and whether Alzheimer's is the cause of one's dementia.

Scientists are investigating several disease markers and diagnostic tests. These biomarkers include genes and proteins, including tau, related to Alzheimer's. New imaging tests are also being developed. These may help indicate whether you have Alzheimer's dementia and how much the disease has progressed. However, more research on these tests is necessary.

Benefit of an early diagnosis

You may feel nervous about seeing a health care provider when you or a family member has memory problems. Some people hide their symptoms, or family members cover for them. It can be difficult to deal with the losses that Alzheimer's dementia can bring. These can include losing independence and driving abilities.

While there's no cure for Alzheimer's, an early diagnosis can still be helpful. Knowing what you can do is just as important as knowing what you can't do. If another treatable condition is causing the memory problems, health care providers can start treatments.

For those with Alzheimer's dementia, doctors can offer drug and nondrug interventions to manage symptoms. Doctors often prescribe drugs that may slow the decline in memory and other cognitive skills. You may also be able to participate in clinical trials.

Also, doctors can teach you and your caregivers about strategies to make your home safer, establish routines, plan activities and manage changes in skills to reduce how Alzheimer's dementia affects everyday life.

An early diagnosis also helps you, your family and caregivers plan for the future. You'll have the chance to make informed decisions on a number of issues, such as:

  • Appropriate community services and resources
  • Options for residential and at-home care
  • Plans for handling financial issues
  • Expectations for future care and medical decisions

When a doctor tells you and your family members about an Alzheimer's diagnosis, they will help you understand Alzheimer's dementia, answer questions and explain what to expect. Your care team can help you figure out ways to maintain independence, health and safety.

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